net: flower: add support for matching cfm fields

Add support to the tc flower classifier to match based on fields in CFM
information elements like level and opcode.

tc filter add dev ens6 ingress protocol 802.1q \
	flower vlan_id 698 vlan_ethtype 0x8902 cfm mdl 5 op 46 \
	action drop

Signed-off-by: Zahari Doychev <zdoychev@maxlinear.com>
Reviewed-by: Simon Horman <simon.horman@corigine.com>
Reviewed-by: Ido Schimmel <idosch@nvidia.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>